Tiltable specimen holding device for electron beam apparatus



Jan 18, 1955 YoRlAKl NAGAHAMA 3,230,365

TILTABLE SPECIMEN HOLDING DEVICE FOR ELECTRON BEAM APPARATUS 3 Sheets-Sheet l Filed Feb. 19, 1963 Jan' 18, 1966 YoRlAKl NAGAHAMA 3,230,365

TILTABLE SPECIMEN HOLDING DEVICE FOR ELECTRON BEAM APPARATUS Filed Feb. 19, 1963 5 Sheets-Sheet 2 Jam 18 1966 YoRlAKl NAGAHAMA 3,230,355

TILTABLE SPECIMEN HOLDING DEVICE FOR ELECTRON BEAM APPARATUS 3 Sheets-Sheet 5 Filed Feb. 19, 1963 A N Pl Fig.7

Fig..9

Fig.8

The invention relates to a specimen tilt-ing device for use in electron beam apparatus such as electron microscopes, electron diffraction cameras, etc.

In conventional specimen tilting devices such as are employed in conjunction with electron beam apparatus and particularly electron microscopes and diifration cameras, a specimen may be tilted or inclined about the optical axis of the device only in one direction perpendicular to the tilting device. Since the specimen may be tilted in one direction only, such apparatus is not satisfactory for use in studying crystalline specimens that possess anisotropic structures.

By ymeans of the unique apparatus of the present invention, it is possible to study the crystal configurations of a specimen in any of its crystal orientations. It has been considered to be impossible to effect such observations by employing the prior known techniques.

It is, therefore, the object of the present invention to provide a specimen holding device for an electron beam apparatus, such device being capable of tilting the specimen in any direction at any desired angle with respect to the optical axis.

Another object of the present invention is to provide a specimen holding device that provides means to effect conical movement of the specimen with respect to an optical axis so that the specimen may be tilted to any desired angle.

A further object of this invention is to provide means for inserting a specimen deeply into the objective lens pole piece of an electron beam apparatus so as to eliect a short focal length that will provide high resolution and additionally, to provide means for tilting the specimen.

A still further object of the present inventon is to provide specimen holding means for electron beam apparatus that may be tilted by manipulation from outside the apparatus so that the specimen may be tilted within the optical axis of the apparatus without'breaking the Vacuum maintained within.

Another object of this invention is to provide a tiltable specimen holding device that is capable of holding a specimen in the plane of the tilting axis and which will effect an accurate inclination to the specimen in any direction in respect to an optical axis.

In addition, the moving parts of the specimen holding device of the present invention is provided with appropriate friction alleviating means that provides smooth operation to `all sliding parts, but which is not susceptible to vaporization in the vacuum customarily employed in electron beam apparatus.

Other objects and advantageous features of the specimen holding device of the present invention will be obvious from the following description and the drawings wherein:

FIGURE l is a diagonal perspective view partially in section of an apparatus embodying the novel features of the present invention;

FIGURE 2 is a top plan view of the apparatus of FIGURE l;

FIGURE 3 is a longitudinal sectional view of the apparatus of FIGURE l;

FIGURE 4 is a top cross-sectional view illustrating the pivot mechanism of the apparatus of FIGURE 1;

ice

FIGURE 5 is a diagonal perspective view partially in section of a ring-shape rotary mount designed to tilt the tilting cartridge of the apparatus lof FIGURE 1 to any desired angle;

FIGURE 6 is a bottom plan view of the ring-shaped mount which accommodates the tilting cartridge of the apparatus of FIGURE l;

FIGURE 7 is a longitudinal sectional view of an apparatus similar to that of FIGURE l, but possessing additionally improved lubricating means;

FIGURE 8 is an enlarged view of the Section A shown in FIGURE 7, and

FIGURE 9 is an enlarged view of the Section B shown in FIGURE 7.

In each of the figures, a tilting cartridge is identified as 1. Inside such tilting cartridge 1, there is shown to be inserted a specimen holder 2 which can be mounted and remove-d whenever desired by the manual operation of an operating rod (not illustrated) from outside the housing of the electron beam device. At the lower end of the specimen holder 2, a specimen 3 to be examined is held by a cap 4. The cap 4 is provided with perforations that permit the transmission of an electron beam (as shown in FIGURES 1, 3 and 7) to intercept the specimen 3.

The member 5 as shown in FIGURE 3 represents the conventional specimen shifter employed within the housing or the column of an electron microscope or other electron beam device. It is, of course, understood that all electron beam devices such as electron microscopes and electron diffraction cameras provide a housing or envelope wherein a substantial vacuum may be created.. Such vacuum is an essential environment in creating an electron beam that may be employed for microscopic examinations. The specimen holder of the present invention is employed in conjunction with and is seated within the conventional specimen shifter 5.

In the apparatus of the present invention, a drum-shaped mounting base 6 is provided with a depending cylindrical section formed with a smaller external diameter than its top opening. The mounting base 6 lis also formed within rim 6a, which is, in turn, seated on the specimen shifter 5 (see FIGURE 3).

The lower part of the above-mentioned cylindrical section of mounting base 6 depends into the objective lens pole piece 7 of an electron beam device (in the present embodiment an electron microscope). A tilting cartridge 1 is positioned within the mounting base 6, and consequently, is also inserted deeply into the pole piece 7. As a result, the specimen 3 is deeply positioned inside the pole piece 7 and the focal length of the objective lens is consequently short enough to obtain a high resolution` A ring-shaped body 8 is coaxially positioned between the lower part of the tilting cartridge 1 and the lower part of the cylindrical section of the mounting base 6, and the ring-shaped body 8 pivotally supports the specimen 3 and the specimen supporting members.

The ring-shaped body 8 is provided with a total of 4 pivots, 9, 10, 11 and 12, the former 2 and the latter 2 arranged on the same level in such a way that they cross each other at right angles at the optical axis. See FIG- URES 1, 3, 4 and 7, particularly FIGURE 4.

The pivots 9 and 10 bear on the pillows 13 and 14 that are provided in the exterior wall at the lower end of the tilting cartridge 1.

The pivots 11 and 12 bear on the pillows 15 and 16 provided in the interior wall of the cylindrical portion at the lower end of the mounting base 6.

The pillows 13, 14, 15 and 16 are made of materials such as sapphire or metal which alleviate friction.

The tilting cartridge 1 and consequently the specimen holder 2 pivotally mounted in the manner described above, may be tilted in any direction.

The ring-shaped body 8 is preferably made from elastic material, such as Phosphor bronze. In assembling the above-described pivotal mechanisms, if the ring-shaped body 8 is fabrica-ted from a resilient material, it may be distorted to assume an oblong form such as shown in FIGURE 4. Since the ring 8 is resilient, it has a tendency to resume its original circular or ring-shape. Hence, the distortion provides the ring-shaped body S with a force that acts outwardly in the up and down direction of the paper plane of FIGURE 4 and inwardly in the right and left direction. Thus, the pivots 9, It), 11 and 12 respectively, are urged towards the pillows 13, 14, 15 and 16 to provide tightly mounted members, and consequently, the bearing section as shown in FIGURE 4 is tightly assembled.

As may be observed, when a specimen is positioned within the pivot mechanism on the same level as each set of pivot members, it can be tilted in any desired direction between 4 pivot assemblies. In other words, since it can be pivoted or tilted along intersecting pivot axes, it may be pivotally moved to assume any intermediary tilted position.

In the application of a tilting mechanism in an electron beam device such as an electron microscope, it is necessary to know the degree and direction of inclination of the specimen. There is positioned about the tilting cartridge 1, a ring-shaped mount 19 that is provided with a cone-shaped opening 29 through which cartridge 1 and the accompanying specimen holder 2 project. When the tilting cartridge 1 is tilted, it is pushed towards the inner wall of the ring-shaped mount 19 by a supporter rod 28 and the up and down motion of the ring-shaped mount 19 varies the inclination angle of the tilting cartridge 1.

The ring-shaped mount 19 is disposed to be raised and lowered in a manner which will be described in fuller detail herebelow. It may be seen, particularly in FIG- URE 3, that the angle of inclination of the tilting cartridge 1 becomes greatest, or is at a maximum when the ring-shaped mount 19 is in its lowest position (as shown in FIGURE 3). The angle of inclination becomes smaller as the ring-shaped mount 19 is raised and reaches its minimum when the ring-shaped mount reaches the highest position (limited by bolts 22a, 22h and 22e) as illustrated with the assumptive lines in FIGURE 3.

A ring-shaped rotary mount or support 1S having spiral guide rails 17a, 17b and 17C whose cross-sections take the form of an inverted V (see FIGURE 5) is mounted within the mounting base 6 in such a way that the rotary base 18 may be freely rotated.

The ring-shaped body 19 is provided with a flange 20 and legs 21a, 2lb and 21C having V-shaped grooves formed in their lower surfaces disposed to receive the V- shape rails 17a, 17b and 17C of the rotary base 18. The number of legs 21 is, of course, optional and the exact arrangement of legs 21a, 2lb and 21C may be varied in any manner that may be provided to be desirable (see FIGURE 6).

As shown by FIGURE 3, the guide rail 17a keeps in contact with the leg 21a and the guide rail 17b with the leg 2lb (see FIGURE 7) and, of course, leg 21e contacts rail 17C. The legs 21a, 2lb and 21e lare disposed to slide on the rails 17a, 17b and 17C respectively. Accordingly, up and down motion of the flange 20 and the ring-shaped body 19 is determined by the position of the legs 21a, 2lb and 21C on the ridges of the respective spiral guide members, (rails 17a, 17h and 17e). When the legs 21 (a, b and c) are placed at the highest point of their respective ridges, the flange 20 and ring-shaped body 19 are positioned at their highest possible elevation, and while in this position, the angle of inclination of the tilting cartridge is at a minimum. 0n the other hand, when the legs 21 (a, b and c) are seated at the lowes-t point on the rails 17 (a, b, and c), the angle of inclination is at its maximum.

Positioned as projected through appropriate perforations in flange 2t) of ring-shaped mount 19 and rigidly attached to the mounting base 6 are three vertically positioned retaining bolts 22a, 22h and 22C. Bolts 22a, 22h and 22C are provided with bolt heads that limit the height that may be obtained from the ring-shaped mount 19 and flange 20.

yIn order to provide pressure disposed to urge the ringshaped mount 19 downwardly, spring members 23a, 23b and 23C are positioned within appropriate openings a, b and c respectively, within the ring-shaped mount 19 as shown in particular by FIGURE 6. The springs 23a, 23b and 23C are attached to or hooked over the top surface of the ring-shaped mount 19 and are attached at their other end to the mounting base 6. The springs 23 are maintained under tension, and accordingly, such tension will increase as the ring-shaped mount 19 is elevated so that downward pressure will be constantly present. Appropriately disposed cogs positioned in the upper portion of ring-shaped mount 18 are meshed with the teeth of a bevel gear 25 that is connected with a knob (not shown) positioned outside the housing of the electron beam apparatus which is disposed to effect rotation to the gear 25 through a universal joint (illustrated at 24 in FIGURE 2). The clockwise rotation of the exterior knob will lcause appropriate rotation of the bevel gear 25 to effect clockwise rotary mo-tion of the ring-shaped rotary mount 13 as shown by its position in FIGURES 1 and 5. Such rotation as may be seen will cause the ring-shaped body 19 to shift upwardly as opposed tothe springs 23 (a, b and c) and as limited by the heads of bolts 22 (a, b and c). The counter-clockwise rotation of the knob and its aforesaid bevel gear 25 will cause the ring-shaped body 19 to shift downwardly as urged by the springs 23.

The following explanation describes the detailed mechanical functioning that effects the varying tilting and orientation of the specimen.

There is positioned on the upper periphery of the mounting base 6 a ring-shaped mount 26 (hereinafter called the rotary mount) having a crown gear disposed for horizontal rotation.

Positioned about the outer periphery of the tiltable cartridge 1 is a ring-shaped tiltable cartridge holder 27 which is disposed to rotate. The ring-shaped tiltable cartridge holder 27 is connected to the rotary mount 26 by means of a leaf spring 28, one end of which is attached to the rotary imount 26 and the other end of which is attached to the tiltable cartridge holder 27. The leaf spring 2S will hereinafter be called the ela-Stic supporting rod.

r1`he tilting cartridge 1 is urged by the spring action of the elastic supporting rod 28 toward the inner surface of the ring-shaped mount 19 and thus the tilting cartridge 1 is maintained in an inclined position. It will be appreciated that the spring action of the elastic supporting rod 28 may be disposed to urge the tilting cartridge 1 towards any desired position along the inner surface 29 of the ring-shaped mount 19 without affecting the function of these members.

The crown gears of the rotary mount 26 are meshed with the teeth of gear 31 connected to a knob (not shown) provided outside the housing of the electron beam device. Rotation of the knob effects rotation of the gear 31 through a universal joint (illustrated at 30 in FIG- URE 2). Rotation of the gear 31 effects rotation of the rotary mount 26 and such rotation may be in either direction, clockwise or counterclockwise. Rotation of the rotary mount 26 is transmitted through the tiltable cartridge holder 27 and the elastic supporting rod 28 to the tiltable cartridge 1. The tiltable cartridge 1 is disposed to slideably rotate within the tiltable cartridge holder 27 so that rotation of the rotary mount 26 causes the tiltable cartridge 1 to effect a conical locus about its central axis. Consequently, that portion of the specimen 3 located at the bottom of the `specimen holder 2 which crosses the optical axis of the electron beam device may be inclined in any direction. It is also evident from the above description that the specimen 3 is intercepted not only by the optical axis, but also the axis of inclination of the specimen.

It is obvious from the above description that the system and apparatus of the present invention is designed and disposed to permit the change of the annular inclination and the direction of inclination separately, in an easy and prompt manner.

In addition, since the apparatus and system of the present invention requires no complex manipulations to incline the tilting cartridge 1 or to incline the specimen in any desired direction, it effects a significant improvement in the eflieiency of carrying out a continuous observation of a specimen in an electron beam device such as an electron microscope or an electron diffraction camera.

Also, since the apparatus of the present invention is disposed in a manner so that the axis of inclination of the specimen is on a level with the specimen surface, the specimen is not greatly influenced by external vibration. Further, since the pivotal apparatus of the present invention is inserted deeply into the objective lens pole piece of the electron beam device, it is possible to shorten the focal distance of the objective lens so that the resulting power of the electron microscope or similar apparatus can be markedly improved.

As stated above, in an electron beam device, such as an electron microscope or an electron diffraction camera, it is necessary to provide a substantial vacuum in the area of the specimen and electron beam. Where a specimen tilting device such as presently described is employed in such vacumm, it is not desirable to employ the usual liquid or oil base lubricants since the vacuum causes such substances to vaporize. Such vapors have adverse effects on the electron beam and contaminate the specimen. However, since the apparatus of the present invention possesses sliding surfaces such as the surface between the tiltable cartridge holder 27 and the tiltable cartridge 1, and the surfaces between the ring-shaped body 19 and the tiltable cartridge 1, some lubrication is required.

A further embodiment of the present invention is the use of plastic materials to insure smooth sliding between the respective sliding sections, particularly as illustrated in FIGURES 7, 8 and 9 so that all of the sliding sections or surfaces are highly friction resistant. The use of lubricating oils on the sliding surfaces is avoided by the effective use of the friction resistant properties of plastics.

FIGURE 7 is a cross-sectional view of an apparatus embodying the features of the present invention which, in this instance, includes a plastic material on the sliding surfaces. FIGURES 8 and 9 show enlarged views of areas A and B of FIGURE 7.

Such plastic surfaces may be provided to the sliding sections that consist of the area wherein the legs 21a, 2lb and 21e contact the guide rails 17a, 1711 and 17e, or a part of the holder of such adjacent slide parts may be constructed of an appropriate plastic material alleviating the necessity of ysuch a coating.

Where the ring-shaped tiltable cartridge holder 27 contacts the tiltable cartridge 1, there is provided a ringshaped plastic body 32 having a U-shaped cross-sectional area to serve the purpose of providing a friction resistant plastic surface between such members (see FIGURE S).

FIGURE 9 shows the inner circumferential section 29 of the ring-shaped mount 19 as tted with a cylindrical plastic material 33 appropriately shaped to t such surface. When the inner circumferential section 29 is provided with a plastic material as shown, the tiltable cartridge 1 slides easily within the area 29. Since it is not possible for such plastic materials to evaporate in the manner of liquid oils, no adverse effects are produced on the specimen due to vaporization of the lubricating media.

The plastic friction reducing coating can be applied, for example, by coating the sliding surfaces with Teflon (polytetrauoroethylene) or the like, or by mixing such plastic materials with fillers such as glass fiber and forming such mixtures under pressure to provide desired mechanical properties.

By employing the friction resistant coatings as described above, it may be said that the accuracy of positioning a specimen by the use of the apparatus of FIGURE 1 has been remarkedly improved, particularly as compared with conventional systems.

It is to be understood that the term cartridge as it is used in the present specification and claims is inclusive of any suitable receptacle that may be employed in the manner described. For example, the term tiltable cartridge includes a funnel-shaped member such as is shown at 1 in the accompanying drawings, or any member that is suitable for such use. The term specimen cartridge encompasses in addition to member 2 of the drawings, any other suitable container or receptacle that will serve the purpose of holding specimens for electron microscopy.

I claim:

1. A tiltable specimen holding device for use within the housing of an electron beam apparatus comprising,

(a) two sets of pivot means, each set comprising spaced opposing pivot points, said pivot points being positioned orthogonally with respect to the optical axis of said device and the axes between the sets of said opposing pivot points being disposed to define a substantially common plane;

(b) mounting means consisting of (1) a conically shaped cartridge to hold the specimen, and

(2) means for mounting said cartridge in said pivot means so that said specimen cartridge may be tilted along the axes of both of said pivot means while maintaining one surface of said specimen within said optical axis and maintaining at least one point on said surface within said common plane; and

(c) tilting means comprising,

(l) a ring-shaped mount positioned around said cartridge so that said cartridge bears on the inside surface of said ring-shaped mount to limit the angle of inclinatiton of said cartridge,

(2) means for adjusting the position of said ringshaped mount along said optical axis in respect to said cartridge so as to vary the angle of inclination; and

(3) a cartridge holder rotatable about said optical axis and engaging said cartridge at a position spaced from said pivot means for tilting the cartridge against the ring-shaped mount.

2. A tiltable specimen holding device as described in claim 1 in which said cartridge holder comprises,

(a) a ring rotatably seated on the device and surrounding said cartridge,

(b) a sleeve engaging and rotatable about the outer surface of said cartridge, and

(c) a resilient arm connected to said ring and said sleeve and resiliently pressing said cartridge against said ring-shaped mount so that upon rotation of said ring said cartridge will define a conical motion in respect to said optical axis.

3. A tiltable specimen holding device as described in claim 2 in which at least one of the opposed surfaces of the cartridge and sleeve has an insert of plastic material having a low coefficient of friction.

4. The structure claimed in claim 1 wherein said ringshaped mount comprises (a) a ring-shaped rotary support rotatably positioned around and spaced from said cartridge and having a plurality of spiral guide rails that gradually increase 5. A tiltable specimen holding device as described in in height, claim 4 in which at least one of the opposed `surfaces be- (b) a plurality 0f legs depending from Said mount, each tween said legs and said guide rails has an insert of p1estie leg Sliding 011 011e 0f Said `Spiral guide fails S0 that material having a low coecient of friction.

when said legs are seated on the highest elevation 5 of said spiral guide rails, said ring-shaped mount is References Cited by the Examiner elevated and allows a minimum angle of lnclination of said tiltable cartridge, and when said legs are at UNITED STATES PATENTS the lowest elevation of said spiral guide rails, said 2,423,158 7/ 1947 Runge et al Z50-49.5 ring-shaped mount allows a maximum angle of in- 10 2,499,019 2/1950 Dornfeld Z50-49.5

clination of said tiltable cartridge, and

(c) means for effecting rotation of said ring-shaped rotary support from outside of said housing so that R 4I PH G NILSON, Primary kammen said ring-shaped mount may be raised and lowered on said spiral rails. 15 FREDERICK M. STRADER, Examiner.

3,086,112 4/1963 Riecke Z50-49.5 

1. A TILTABLE SPECIMEN HOLDING DEVICE FOR USE WITHIN THE HOUSING OF AN ELECTRON BEAM APPARATUS COMPRISING, (A) TWO SETS OF PIVOT MEANS, EACH SET COMPRISING SPACED OPPOSING PIVOT POINTS, SAID PIVOT POINTS BEING POSITIONED ORTHOGONALLY WITH RESPECT TO THE OPTICAL AXIS OF SAID DEVICE AND THE AXES BETWEEN THE SETS OF SAID OPPOSING PIVOT POINTS BEING DISPOSED TO DEFINE SUBSTANTIALLY COMMON PLANE; (B) MOUNTING MEANS CONSISTING OF (1) A CONICALLY SHAPED CARTRIDGE TO HOLD THE SPECIMEN, AND (2) MEANS FOR MOUNTING SAID CARTRIDGE IN SAID PIVOT MEANS SO THAT SAID SPECIMEN CARTRIDGE MAY BE TILTED ALONG THE AXES OF BOTH OF SAID PIVOT MEANS WHILE MAINTAINING ONE SURFACE OF SAID SPECIMEN WITHIN SAID OPTICAL AXIS AND MAINTAINING AT LEAST ONE POINT ON SAID SURFACE WITHIN SAID COMMON PLANE; AND (C) TILTING MEANS COMPRISING, (1) A RING-SHAPED MOUNT POSITIONED AROUND SAID CARTRIDGE SO THAT SAID CARTRIDGE BEARS ON THE INSIDE SURFACE OF SAID RING-SHAPED MOUNT TO LIMIT THE ANGLE OF INCLINATION OF SAID CARTRIDGE, (2) MEANS FOR ADJUSTING THE POSITION OF SAID RINGSHAPED MOUNT ALONG SAID OPTICAL AXIS IN RESPECT TO SAID CARTRIDGE SO AS TO VARY THE ANGLE OF INCLINATION; AND (3) A CARTRIDGE HOLDER ROTATABLE ABOUT SAID OPTICAL AXIS AND ENGAGING SAID CARTRIDGE AT A POSITION SPACED FROM SAID PIVOT MEANS FOR TILTING THE CARTRIDGE AGAINST THE RING-SHAPED MOUNT. 